STORY OF A BERM TYPE REVETMENT DESIGN ORDU GİRESUN AIRPORT, THE FIRST SEA FILL AIRPORT OF TURKEY Mustafa Esen1, Işıkhan Güler2, Hülya Karakuş Cihan3 and Erdinç Söğüt4 Ordu Giresun Airport is the first airport of Turkey that is completely built on a sea fill area situated at the Black sea coast of Turkey and at equal distances to Ordu and Giresun cities. The reclamation covers 1.6 million m2 area that is surrounded with a total of 8.6 km revetment. The longest part of the revetment which is in parallel with the shoreline and at the offshore side of the reclamation area, is planned as a berm type revetment. In this sense, the preliminary cross section provided at the tender stage is checked, modifications are performed considering several criteria such as economics, performance, availability of rocks, etc. In addition to the design stages, several cross sections together with the suggested modifications are checked with laboratory tests. This paper covers the design stages where this criteria is taken into account, laboratory tests and the performance of the cross section during construction stages. Keywords: berm type revetment; sea fill; wave overtopping INTRODUCTION Ordu Giresun Airport is the first airport that is built on reclamation coastal area. The project site is located at the Black Sea coast of Turkey (Figure 1). A closer look at the site with an emphasis on general layout of the reclamation area is provided in Figure 2. It should be noted that the reclamation stages were not finished when the satellite image wass taken. Thus, it looks as if some ponds were left unfilled in the general layout. As a result, in order to have an idea about the final look of the airport, Figure 3 is provided. The need to build an airport is an outcome of the high demand from residents of Ordu and Giresun cities in order to reduce their travel time to the nearest airports, which is Samsun Çarşamba Airport for residents of Ordu and Trabzon Airport for residents of Giresun. Another reason is to reduce the high number of passengers for the existing nearby airports that is especially observed during summer time. Figure 1. Location of Ordu Giresun Airport. As a result of the above given needs and reasons, Directorate General of Infrastructure Investments under the Ministry of Transport, Maritime Affairs and Communication went out to tender. The first phase of the tender consisted of the design and construction of: 1,600,000 m2 sea reclamation area, 3.1 km runway, 8.6 km revetment At tender stage, Directorate General of Infrastructure Investments provided the tenderers with the preliminary design of the reclamation area, berm type revetment and other relevant preliminary designs. 1 Yüksel Proje Uluslararası A.Ş., Birlik Mah. 450. Cad No: 23 Çankaya, Ankara, 06610, Turkey 2 Yüksel Proje Uluslararası A.Ş., Birlik Mah. 450. Cad No: 23 Çankaya, Ankara, 06610, Turkey 3 Yüksel Proje Uluslararası A.Ş., Birlik Mah. 450. Cad No: 23 Çankaya, Ankara, 06610, Turkey 4 Yüksel Proje Uluslararası A.Ş., Birlik Mah. 450. Cad No: 23 Çankaya, Ankara, 06610, Turkey 1 2 COASTAL ENGINEERING 2016 Cengiz İnşaat A.Ş. was awarded the contract after the conclusion of the tender stages and Yüksel Proje Uluslararası A.Ş. was awarded as the designer by Cengiz İnşaat A.Ş. Figure 2. General Layout of Ordu Giresun Airport. Figure 3. Final Layout of Ordu Giresun Airport. BERM TYPE REVETMENT DESIGN Introduction Berm type revetment that was designed to protect the sea reclamation area is one of the few experiences of its kind in Turkey and there was little information to put into design beforehand. Thus, before initiation of design stages, a thorough literature survey were completed about berm type revetment design and construction. After collecting the necessary information, the design stages were initiated by studies on wind and wave statistics to obtain the extreme wave estimations. In this stage, the influence of several wind sources and spatial wind data on extreme waves were examined in detail. The following stage was to confirm if the preliminary design was performing as required and if there was any need to make modifications under the determined extreme waves. The results indicated that the preliminary design was conservative. Thus, several suggestions to the cross section of the berm type revetment were suggested to obtain a similarly safe solution but an economical one. Starting with the preliminary cross section provided at the tender stage and the suggested cross section, several cross sections were physically tested under various wave conditions in the facilities of Directorate General of Infrastructure Investments. This part was in the care of Directorate General of COASTAL ENGINEERING 2016 3 Infrastructure Investments and the results were shared with the designer. The suggested cross section was slightly modified considering the results of physical model tests and approved by the ministry officials. Extreme Wave Estimation Studies In order to obtain the extreme wave data, ECMWF wind data for 9 coordinates and in-situ wind measurements of two nearby coastal meteorological stations were considered (Figure 4). The data of each point and source was used to understand the influence of the data sources and the impact of spatial wind data sets on design wave estimation studies. This study eventually provided the design team with a final and clear idea about applicability of in-situ wind measurements of two nearby coastal meteorological stations as well as the influence of boundary conditions on ECMWF wind data for the site. It should be noted that, the wind measurements of two nearby coastal meteorological stations were carried to the sea with a land-sea conversion approach (Hsu, 1981) to obtain the wind data at 10 m elevation above MSL (mean sea level). It was assumed that the wind direction does not change in such a land-sea conversion. Figure 4. Coordinate and locations of two coastal meteorological stations and ECMWF data points. In order to understand the difference between wind data sets and their applicability in the wave estimation studies, wind roses are initially drawn as in Figure 5. Since the wind roses for each ECMWF coordinate were almost similar, only wind rose obtained for 45.10°N-38.20°E was given in Figure 5. The related figure indicates that the wind speeds measured at two nearby coastal meteorological stations are lower than that obtained from ECMWF point and the wind directions were different for all of the wind data sources. Even though it was clearly deduced that ECMWF should be used as wind data source for the wave estimation studies, all of the data sources were considered in extreme wave estimation studies to have an additional comparison. 4 COASTAL ENGINEERING 2016 Figure 5. Wind roses for two nearby coastal meteorological stations and one ECMWF coordinate. The studies were continued with extreme wave estimations. In this part of the design, the impact of distance between wind data coordinates and land was analyzed by taking into account different ECMWF points. Moreover as mentioned above, in-situ wind measurements of two nearby coastal meteorological stations were also considered for further discussion. For wave estimation studies, W61 Numerical Model, a Visual Fortran based model that was developed in Ocean Engineering Research Center, Civil Engineering Department, Middle Technical University was used. Wind data set for one coordinate and effective fetch distances of each directions separated with 22.5° are the main inputs of W61. The effective fetch distances are given in Figure 6. W61 produces individual and cumulative storm data summaries, yearly wave data sets for long term studies and maximum wave data set for extreme wave studies as outputs. From these data sets, wave steepness data was determined (Table 1) and this is followed by extreme wave statistics. The results of the extreme wave studies are given in Table 2. Wave heights are provided with 90% confidence intervals and extreme wave data only for 50 and 100 year return periods are given in Table 2. Based on the results, it was decided to use ECMWF wind data for 41.25°N-38.20°E coordinates for the following design stages. DIRECTION EFF.FETCH (km) WNW 496 NW 655 NNW 478 N 373 NNE 316 NE 304 ENE 267 E 152 Figure 6. Effective fetch directions and distances. COASTAL ENGINEERING 2016 5 Table 1. Wave steepness that are obtained for different data sources and coordinates. SOURCE Coordinates Duration Ave. Wave Steepness Ordu Met. Sta. 40.59°N-37.54°E 1965-2009 0.0371 Giresun Met. Sta. 40.55°N-38.23°E 1967-2009 0.0419 ECMWF 41.00°N-38.10°E 1983-2010 0.0410 ECMWF 41.20°N-38.10°E 1983-2010 0.0377 ECMWF 41.30°N-38.10°E 1983-2010 0.0450 ECMWF 41.50°N-38.10°E 1983-2010 0.0444 ECMWF 41.30°N-38.20°E 1983-2010 0.0393 ECMWF 41.40°N-38.20°E 1983-2010 0.0409 ECMWF 41.50°N-38.20°E 1983-2010 0.0405 ECMWF 41.20°N-38.30°E 1983-2010 0.0437 ECMWF 41.30°N-38.30°E 1983-2010 0.0427 Table 2. Results of extreme wave statistics. SOURCE Deep water significant wave height, Hs0 (m) Deep water significant wave period, Ts (s) Rp = 50 years Rp = 100 years Ordu Met. Sta. 2.86 ± 0.30 3.06 ± 0.35 7.03 7.27 Giresun Met. Sta. 3.41 ± 0.58 3.79 ± 0.67 7.22 7.62 ECMWF 4.31 ± 1.08 4.87 ± 1.26 41.00°N-38.10°E 8.20 8.73 ECMWF 6.56 ± 0.96 7.07 ± 1.11 41.20°N-38.10°E 10.56 10.96 ECMWF 6.59 ± 0.91 7.07 ± 1.06 41.30°N-38.10°E 9.69 10.04 ECMWF 6.84 ± 0.88 7.30 ± 1.03 41.50°N-38.10°E 9.94 10.27 ECMWF 6.52 ± 0.87 6.98 ± 1.02 41.30°N-38.20°E 10.31 10.67 ECMWF 6.76 ± 0.96 7.24 ± 1.05 41.40°N-38.20°E 10.30 10.65 ECMWF 6.90 ± 0.90 7.37 ± 1.05 41.50°N-38.20°E 10.45 10.80 ECMWF 6.63 ± 0.97 7.14 ± 1.13 41.20°N-38.30°E 9.86 10.24 ECMWF 6.34 ± 0.97 6.76 ± 0.94 41.30°N-38.30°E 9.75 10.08 Wave Transformation Studies Extreme deep water waves for ECMWF 41.25°N-38.20°E coordinates were transported to nearshore by SWAN and the nearshore design wave data in front of the revetment for different water depths were determined.